[Field of the Invention]
The present invention relates to an engine fuel injection device suitable for particularly multi-cylinder fuel injection in an internal combustion engine in a motorcycle or an outboard motor.
[Description of the Related Art]
A fuel injection type multi-cylinder engine of such a kind is usually controlled by an ECU (engine control unit) so that a fuel injection is performed at a most appropriate timing in accordance with a piston position per each cylinder after discrimination of cylinders. If the fuel injection is desired to be performed at an earliest possible timing for improvement of engine startability, there is a technique in which fuel injections are performed simultaneously in respective cylinders after an ECU is activated, before cylinder discrimination.
If a battery is mounted as a power supply for driving a fuel injector in order to perform a fuel injection, a power necessary for simultaneous driving of a plurality of injectors is secured. On the other hand, for example, with regard to a motorcycle or an outboard motor, in a model whose engine is started without usage of a battery, that is, in a batteryless engine, it is compelled to depend on manpower (kick starter in the motorcycle, hand-operated recoil starter in the outboard motor). In such a case, a crankshaft of the engine is forcibly rotated by hand, and an injector being an engine load is driven by power generation of an alternator or an alternating current generator (ACG).
[Patent Document 1] Japanese Laid-open Patent Publication No. 09-32605
When the engine is started by hand or the like as described above, an engine rotation number at that time is low, that is, a crankshaft rotation speed is slow, and thus it becomes practically difficult to secure a power necessary to drive the plural injectors by the ACG. As a measure thereof, it has been conventionally necessary to increase a size of the ACG, for example, to enlarge its power generation amount.
Note that Patent Document 1 discloses an actuation time control method in a multi-cylinder engine of such a kind. It is a method where a fuel injection of a predetermined amount is each performed asynchronously to all cylinders in response to a cylinder detection signal in an actuation mode.